The present invention disclosed herein relates to a solar cell, and more particularly, to a method of manufacturing a solar cell capable of improving characteristics of a copper indium gallium selenide (CIGS) based thin film at a low temperature.
Due to the lack of silicon raw material according to the growth of a solar cell market, a thin film solar cell receives great attentions. The thin film solar cell may be classified into an amorphous or crystal silicon thin film solar cell, a CIGS based thin film, a CdTe thin film solar cell, and a dye-sensitized solar cell, according to its material. A light absorbing layer of the CIGS based thin film includes a Group I-III-VI2 compound semiconductor (for example, CuInSe2, Cu(In,Ga)Se2, Cu(Al,In)Se2, Cu(Al,Ga)Se2, Cu(In,Ga)(S,Se)2, and (Au,Ag,Cu)(In,Ga,Al)(S,Se)2) and its typical material includes CuInSe2. Also, the light absorbing layer has a direct transition energy bandgap and a high light absorption coefficient such that it is possible to manufacture a highly efficient solar cell with a 1 to 2 μm thin film.
The CIGS based solar cell has higher efficiency than a partly commercialized amorphous silicon or CdTe thin film solar cell and it is well known that its efficiency is close to that of a typical polycrystal silicon solar cell. Additionally, the CIGS based solar cell may be formed of a material whose price is less expensive than other materials for solar cells and may be flexibly manufactured. Also its performance will not be deteriorated for a long time.